Direct Code Execution: Revisiting Library OS Architecture for Reproducible Network Experiments

We describe the first capability, to our knowledge, to execute nearly unmodified applications and Linux kernel code in the context of a widely-used open source discrete event network-ing simulator (ns-3). We propose Direct Code Execution (DCE), a framework that dramatically increases the num-ber of available protocol models and realism available for ns-3 simulations. DCE meets the goals recently proposed for fully reproducible networking research and runnable pa-pers, with the added benefits of 1) the ability of completely deterministic reproducibility, 2) the scalability that simu-lation time dilation offers, 3) capabilities supporting auto-mated code coverage analysis, and 4) improved debugga-bility via execution within a single address space. In this paper, we describe in detail DCE, report on packet process-ing benchmarks and showcase key features of the framework with different use cases. We reproduce a previously pub-lished Multipath TCP (MPTCP) experiment and highlight how code coverage testing can be automated by showing re-sults achieving 55-86 % coverage of the MPTCP implemen-tation. Then we demonstrate how network stack debugging can be easily performed and reproduced across a distributed system. Our first benchmarks are promising and we believe this framework can benefit the network community by en-abling realistic, reproducible experiments and runnable pa-pers